The primary objective of the UC Davis MIND Institute IDDRC Neurobehavioral Analysis Core (NAC) is to help investigators generate detailed phenotypic characterizations of individuals with Intellectual and Developmental Disabilities (IDD). Phenotypic characterization requires measures that are appropriate for a representative sample of individuals with IDD and are designed, executed, and analyzed with the most precision and fidelity possible. Existing standardized tests, rating scales, and checklists are often not adequate for such characterization and adaptations of such measures or the creation of new measures are required. Moreover, many measures are often applicable to only a very narrow segment of the IDD population of interest. The NAC will assist IDDRC investigators in ensuring that they have the measures needed to generate advanced biobehavioral characterizations that can stand alone, be used to assess environmental contributions to IDD, or provide the evidence base for the development and evaluation of targeted treatments for IDD. To achieve this objective, the NAC will draw on the interdisciplinary expertise and already developed measures of several MIND Institute and UC Davis faculty and staff to provide key services for investigators conducting neurobiological studies of cognition, emotion, language, and other aspects of brain and behavior in human research participants with neurodevelopmental disorders that create IDD.